The present invention is directed to a monitor which operates to trigger an alarm when a patient attempts to leave a bed.
In a hospital setting it is not uncommon for a patient to be prone to falls in leaving a bed or in attempting to walk. All too often, such a patient will not notify hospital nurses that he or she needs help, but will instead attempt to get out of bed and walk without assistance. When this happens, falls and injury to the patient may well result.
The need for a monitor to detect when a patient attempts to leave a hospital bed has been recognized for some time. For example, U.S. Pat. No. 2,784,395 to Gorby discloses a patient fall-out warning device for hospital beds in which a wire is strung over the bed. A patient attempting to leave the bed breaks the wire, thereby triggering the warning device.
A second approach of the prior art has been the use of pressure-sensitive pads either in or under the mattress of a hospital bed. U.S. Pat. No. 4,295,133 to Vance, U.S. Pat. No. 4,264,904 to McCoy, U.S. Pat. No. 4,020,482 to Feldl, and U.S. Pat. No. 4,175,263 to Triplett et al are four examples of such prior art pressure-sensitive warning systems.
The prior art approaches to this problem are not without disadvantages. The system disclosed in the Gorby patent, for example, requires the conductor to be strung over the bed. The pressure-sensitive systems described in the Vance, McCoy, Feldl, and Triplett patents are relatively complex, and they provide only an indirect indication of patient movement because they sense pressure rather than the position of the patient.